Nutritional Science: Food Groups, Metabolism, and Preservation Techniques

Essential Food Groups and Nutritional Components

Food groups are categorized by their primary nutritional contributions:

• Milk, Milk Derivatives, and Eggs

  Source of proteins, vitamins, and calcium.

• Meat, Poultry, and Fish

  Primarily provide protein.

• Fats and Oils

  Include animal fats (e.g., butter) and vegetable oils. They provide lipids needed when eaten in moderation.

• Cereals, Pulses, Potatoes, and Sugar

  Provide proteins and glucids (carbohydrates).

• Vegetables

  Source of vitamins and fiber.

• Fruit

  Provide glucids (carbohydrates), vitamins, and fiber.

Macronutrients: Energy and Building Blocks

• Glucids (Carbohydrates): Provide energy. Most common forms are starches (found in pulses and potatoes) and sugars (e.g., glucose).
• Fibre: A type of glucid derived from vegetables. Necessary for helping food pass through the intestines.
• Lipids (Fats): Provide energy. Found in vegetable oils (e.g., olive oil) and animal fat (e.g., butter).
• Proteins: The building matter that forms our cells. Sourced from animal and vegetable foods.
• Water: Fundamental component of living matter. Recommended intake is approximately 3 liters a day.

Micronutrients: Vitamins and Minerals

These are required in small quantities:

Vitamins

• VA (Retinol): Found in carrots and spinach.
• VB (Thiamine): Found in eggs.
• VB6 (Pyridoxine): Found in sardines.
• VC (Ascorbic Acid): Found in kiwis.
• VD (Calciferol): Synthesized by the skin.

Minerals

Chemical elements, not part of living matter, needed in small quantities (e.g., sodium, calcium).

Understanding Energy Consumption and Metabolism

Calorie Definition

The amount of heat required to increase the temperature of one gram of water by 1ºC.

Basal Metabolic Rate (BMR)

The certain amount of energy consumed by the body when totally at rest and maintaining a constant temperature.

BMR Calculation Formulas

(W = Weight, H = Height, A = Age)

• BMR (Men): 655 + 13.7 x W + 5 x H - 6.8 x A
• BMR (Women): 655 + 9.6 x W + 1.8 x H - 4.7 x A

Food Preservation and Modern Production Methods

Food Spoilage

Food spoils due to microorganisms, specifically fungi and bacteria.

• Fungi: Responsible for mould growth in food.
• Bacteria: Responsible for rotting, a natural transformation and degradation process of proteins, often resulting in a bad smell.

Preservation Techniques

These methods help food last longer:

Traditional Methods

• Drying (e.g., cod)
• Salting (e.g., ham)
• Smoking (e.g., salmon)

Cold Storage Methods

• Refrigeration: Keeping food in a cold environment.
• Freezing: More effective than refrigeration (typically -10ºC or lower). Microbial action is completely detained.

Sterilization and Additives

• Sterilization Techniques: Methods used for killing microorganisms in food.
• Pasteurization: Applied primarily to milk. Involves heating milk to 80ºC for 30 seconds, killing 99.5% of microorganisms.
• Food Additives: Added in small quantities to food to improve flavor or appearance. Preservatives specifically make food last longer.

Modern Agricultural and Aquaculture Practices

• Greenhouses: Make it possible to obtain up to three annual harvests for some vegetables.
• Pesticides and Herbicides: Used to prevent crops from suffering attacks by insects or competitive weeds.
• Intensive Farming: Animals are fattened in short periods by improving their feeding.
• Fish Factory (Aquaculture): Different kinds of fish are reared. This makes it possible to obtain good quality food in a short period of time and avoids the over-exploitation of natural fishing resources.

Genetically Modified Food

A fragment of DNA from a specific organism is introduced into the DNA of another organism. This process can be used, for example, to create a modified bacteria.

The resulting organism is referred to as Transgenic.